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causes (whether correlated or not with the device itself) Table 1: Indicators for failure of HA cranioplasty
but also, where possible, to suggest countermeasures. implants
Errors Complications
METHODS Incongruous size or shape Infection
Breakage Fistula
We analyzed information regarding failures or complications Dislocation/mobilization Fluid collection: extracranial and/
reported in postmarketing surveillance and clinical or extradural
studies of patients treated worldwide with custom‑made Subdural hematic suffusion
HA cranial implants (Custom Bone Service Fin‑Ceramica Skin ischemia/necrosis/decubitus
Lack of osteomimesis
Faenza, Italy) during the period of 1997‑2013. This analysis
was possible due to an agreement between the relevant HA: Hydroxyapatite
parties in the context of an academic study. No sensitive
information was collected during the research, which was Table 2: Correlation between the anatomical location of
limited to the processing of data regarding adverse events the prosthesis and the incidence of infection
Cases of Rates in total
according to the biomedical device surveillance norms in Implantation site Number of infections infections
cases
[2]
force (MEDDEV‑2). Statistical interpretation of the data (n = 2877) (n) (%) (n = 51) (%)
was performed using IBM SPSS (V19; Chicago, United (%)
States). Fontoparietotemporal 1588 (55) 25 (1.57) 49
Frontal-bifrontal 548 (19) 17 (3.10) 33.3
RESULTS Parietal 231 (8) 3 (1.30) 5.9
Temporoparietal 491 (17) 6 (1,22) 11.8
In the study period, 2877 custom‑made HA devices Occipital 29 (1) - -
were implanted and all adverse events that arose were
collated [Table 1]. The two most common complications Table 3: Chi-square test to compare the infections
were implant fractures (84 cases, 2.9% of the total implant rates of two groups
fitted) and infections (51 cases, 1.77%). Of the fractures, Group Infected implants Implants without infection Total
36 (1.25%) occurred postimplant (within 12 months of Group 1 42 2094 2136
surgery, delayed fracture) and 48 (1.66%) occurred during Group 2 9 742 751
the surgery itself (early fractures). A back‑up was used to Total 51 2836 2887
replace the primary implant in 43 of these cases. Fractures
were not correlated with the size of the cranial defect. Group 1: the HA cranioplasty implant takes relationship with frontal
sinus (frontal, frontoparietotemporal and bifrontal); Group 2: the
A correlation was noted between the occurrence of HA cranioplasty implant does not take relationship with frontal
infection and the implantation site: frontoparietotemporal sinus (parietotemporal, parietal, temporal and occipital). The Chi‑square
in 25 cases (49% of total infections), frontal‑bifrontal in test revealed no significant difference between the two groups (P = 0.1694;
17 (33.3%) temporoparietal in 6 (11.8%) and parietal in OR 1.65). OR: Odds ratio; HA: Hydroxyapatite
3 (5.9%) [Table 2]. However, data analysis did not reveal or fixing of the implant. Regarding the planning, design,
a statistically significant difference regarding implantation and validation phase, the relevant persons (manufacturing
site (Chi‑square test; P = 0.1694; odds ratio = 1.65)
[Table 3]. A further correlation between the time elapsed technician and surgeon) should pay particular attention to the
after surgery and the onset of infection was noted: less following critical steps if such occurrences are to be avoided:
than 6 months in 32 (62.8%) cases, 6 months to 1 year in verification of suitable implant thickness and uniformity of the
3 cases (5.8%), and more than 1 year in 16 cases (31.4%). density distribution of the prosthesis (micro‑ and macro‑pores
Analyzing data for the first postoperative year, it was and interconnection channels), ensuring that the prosthesis
observed that most infections occurred between 3 and perimeter engages the bone margin at all points, the latter
6 months (23 infections, 45%). It was also noted that being a type of ledge upon which the implant should rest
infections were more common in cases of cranial trauma. snugly all round, thereby spreading the forces evenly. Thus,
the prosthesis, in addition to possessing suitable curvature,
DISCUSSION should be tailored to fit the cranial lacuna precisely and
without breaks. Indeed, if this does not occur, in addition to
a lack of osteointegration, the laws of mechanics dictate that
Delayed posttraumatic prosthesis fracture (36/2877) occurred weaker areas with less resistance will arise. Regarding early
with an incidence three‑fold higher than that seen in normal fracture (i.e. during surgery), if one implant breaks, it could
population (3.5‑4.5/1000). The incidence of a second cranial be due to manufacturing/design error, but if both the primary
trauma also seemed to be greater than in normal population and back‑up devices break, surgical error is the more likely
(2/1000), presumably due to the clinical and neurological cause because the possibility of a structural defect affecting
effects of the underlying primary pathology. However, there two separate blocks of HA is remote.
was no discernable correlation between fracture and defect
size, so other issues need to be examined, most likely the Infections were more frequent in trauma patients, not
severity of the head trauma that fractured the skull or surgical surprisingly, because these represent the greater portion
error stemming from a lack of careful planning, positioning, of the population in which custom‑made HA cranial

8 Plast Aesthet Res || Vol 2 || Issue 1 || Jan 15, 2015